Cu/Co Bilayers: Study of the Surface Topography, Optical Dispersion Parameters, and Transitions of Carriers

In this study, Cu and Cu-Co films were prepared using DC Magnetron sputtering system on silicon substrates. Any increase in the roughness and thickness of films would intensify the scattering of the sputtered atoms and consequently, the atoms would lose enough time to find the lowest energy required by each nanoparticle (NP). The height changes on the surface of the scanned films are indicative of the topological phase of the films. According to the results, the films were not smooth that made them undergo a second phase change. The address layer and thickness changes did not have much effect on the degree of isolation. For this reason, the graphs demonstrated close and identical results. All samples display strong light absorption over the entire spectral range, suggesting that they could bide all light-absorber materials. At the peak of approximately 2.7, the cross-point of d(⍺hν)/d(hν) curves yielded optical band gap (Eg) values of 2.68 eV, 2.76 eV, 2.85 eV, and 2.73 eV corresponding to the Samples 1 to 4, respectively. The optical conductivity of the films increased upon increasing the energy. The SEM images confirmed that the obtained cobalt nanocrystals was approximately spherical in shape with an average diameter less than 80 nm.